JP3523068B2 - Local decomposition treatment jig and method for analyzing impurities in sample wafer using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local decomposition treatment jig, and more particularly to a depth profile profile of trace impurities such as chromium, iron, nickel and copper present in a silicon single crystal wafer for semiconductor production. -A wafer disassembly processing jig used for quantitative analysis to know the profile, and not only the depth direction profile as an average value of the entire surface of the wafer,
The present invention relates to a local disassembly processing jig capable of accurately measuring a local profile in the depth direction.

[0002]

2. Description of the Related Art With the recent trend toward higher integration and miniaturization of semiconductor devices, it has been required to keep the impurity concentration of materials such as wafers extremely low. In particular,
Heavy metal elements existing in the vicinity of the surface of the wafer greatly change the basic characteristics of the device, and therefore reduction thereof is strongly demanded. For this reason, even in the analysis of these trace amounts of impurity heavy metal elements, it is required not only to improve the detection accuracy but also to provide detailed information on the distribution state of impurities in the wafer, that is, the impurity concentration profile in the wafer. It has started to be done.

As the analysis of impurity elements in a wafer, surface analysis, depth direction analysis, bulk analysis and the like have been generally carried out in the past.
RF), secondary ion mass spectrometry (SIMS), ICP mass spectrometry (ICP-MS) and other analytical methods. Among the heavy metal impurities analysis of such wafer,
In the depth direction analysis from the wafer surface, conventionally, the whole surface of a sample such as a silicon wafer is sequentially and stepwise decomposed and etched in the depth direction using a decomposition etching chemical such as HF-HNO ₃ mixed acid. Generally, a so-called sequential dissolution method, which is a method of decomposing and volatilizing a Si layer having a predetermined thickness at each stage, recovering and concentrating trace impurities heavy metals dissolved and remaining in the decomposition etching chemical solution, and performing an analysis process, has been generally used.

For example, as described in the magazine “BUNSEKI KAGAKU (Analytical Chemistry), Vol. 43, pp. 173 to 176 (1994)”, a sample wafer is placed in this jig container using a decomposition jig. A predetermined amount of a decomposition etching chemical solution is loaded onto the upper surface of the loaded wafer, and the decomposition S of the chemical solution causes the S of the sample to be sequentially and stepwise from the surface.
The i component is decomposed and volatilized, and the element concentration of the impurity-containing chemical liquid at each stage is quantified by, for example, ICP-MS measurement. Therefore, in this method, since the entire surface of the sample is decomposed, the obtained depth direction impurity concentration profile is inevitably obtained as the average concentration value of the entire surface of the wafer when the sample is a wafer.

This will be described in detail with reference to FIG.
Reference numeral 0 denotes a conventional decomposition processing tool, and this decomposition processing tool 10 is applied to a wafer mounting body 11 having a circular wafer mounting surface and a sample wafer 12 mounted on the wafer mounting body 11. Chemical liquid holding member 1 for holding chemical liquid for etching decomposition
3 and 3. The chemical liquid holding member 13 is formed of a cylindrical body, and the wall portion 13b of the chemical liquid holding member 13 is placed on the outer peripheral portion of the sample wafer 12, so that the chemical liquid for etching decomposition is held on the sample wafer 12. Is configured to. The through opening 13a formed in the central portion of the chemical liquid holding member 13 is the sample wafer 12
Is formed to have a diameter smaller than that of the sample wafer 12, and is formed so as to match the predetermined etching surface of the sample wafer 12. Further, as a material of these members of the jig, generally, polytetrafluoroethylene resin (PTFE) is used from the viewpoint of its chemical solution corrosion resistance and dust resistance.

In order to perform the stepwise decomposition etching of the sample wafer 12 in the depth direction using this jig, the sample wafer 12 is first placed on the wafer holder 11 of the jig, and then, As shown in FIG. 7B, the chemical liquid holding member 1
The wall 13b of the sample wafer 12
Put it on top. In this state, the wall portion forming the through opening 13a of the chemical liquid holding member 13 and the mounted sample wafer 12
A predetermined amount of a chemical solution for etching decomposition is injected into a concave portion formed by the upper surface of the sample wafer 12 and the sample wafer 12 is etched. As described above, in the case of the conventional disassembly processing jig, the disassembly etching processing is performed on almost the entire surface of the sample wafer.

[0007]

By the way, in a wafer that has undergone various steps such as heat treatment, polishing, and grinding, the contamination state such as external contamination during the course of each step is not uniform in the plane, and therefore, recently, Then, the depth direction profile of the local impurity concentration in each in-plane region is required, and the emergence of a local decomposition treatment jig capable of efficiently and reliably performing this analysis is strongly demanded. However, as described above, when the conventional decomposition treatment jig is used, the decomposition etching treatment covers almost the entire surface of the sample wafer, and the depth profile of the local impurity concentration in each in-plane region can be obtained. There was a technical problem that could not be done.

Further, in the conventional decomposition treatment jig, the chemical solution for etching and decomposition is held on the sample wafer by placing the wall of the chemical solution holding member on the outer peripheral portion of the sample wafer. It is configured. However, due to the distortion of the chemical liquid holding member or the flatness of the bottom surface of the wall portion in contact with the wafer, the chemical liquid for etching decomposition leaks to the outside because the wall portion of the chemical liquid holding member does not adhere to the sample wafer. There were challenges.

The present invention has been made in order to solve the above technical problems, and a local decomposition treatment jig for impurity analysis of a wafer or the like from which an impurity concentration depth direction profile for each in-plane region can be easily obtained. To provide. In particular, it is an object of the present invention to provide a local decomposition treatment jig for impurity analysis of a wafer or the like, which can easily obtain an accurate profile in the depth direction of the impurity concentration in each of the outer peripheral region, the intermediate region and the central region of the surface to be treated. . In addition, each of the above three areas is further divided into four, and 12
It is an object of the present invention to provide a local decomposition treatment jig for impurity analysis of a wafer or the like, which can easily obtain an accurate impurity concentration depth direction profile for each region. Further, in the present invention, a local decomposition treatment jig for preventing impurities from leaking to the outside of the etching decomposition chemical and for analyzing impurities such as wafers in which the etching decomposition chemical on the divided processed surface is not mixed is provided. To provide. Another object of the present invention is to provide an impurity analysis method for a sample wafer using a local decomposition treatment jig, which can easily obtain the impurity concentration depth direction profile for each in-plane region.

[0010]

According to the present invention, a wafer mounting surface for mounting a sample wafer on an upper surface of a local decomposition processing jig used for etching decomposition processing of a sample wafer and used for impurity analysis of the wafer. A wafer stage provided with
And a chemical solution holding means for holding a chemical solution for etching and decomposition applied on the sample wafer placed on the wafer mounting body, wherein the chemical solution holding means at least stores the chemical solution for etching and decomposition applied on the sample wafer. comprising a partition plate for holding onto the processed surface of the sample wafer, and a lid for pressing the partition plate surface to be processed of the sample wafer, the partition plate is a wafer
The processed surface of the sample wafer mounted on the mounting body is divided into a plurality of areas.
It is a partition plate that is divided into sections and is a thin plate with a thickness of 3 mm or less.
Formed on the surface of the sample wafer or comes into contact with the surface to be processed of the sample wafer
The partition plate has an edge shape with a thickness of at least 3 mm or less
The lid is formed with an opening for injecting a chemical solution for etching and decomposing on the sample wafer, and is formed so as to be screwed with the outer peripheral side surface of the wafer mounting body. By screwing the
There is provided a local decomposition processing jig, wherein the partition plate is configured to be pressed against the surface to be processed of the sample wafer. As described above, the present invention has improved the jig used in the conventional analysis method in which the entire surface to be processed of the sample wafer is etched and decomposed in the depth direction, and the chemical liquid holding means is provided with a plurality of surfaces to be processed of the sample wafer. By providing a partition plate for partitioning into regions, the etching decomposition solution filling space (recess) on the surface to be processed of the wafer can be divided into a plurality of partition regions for analysis. In particular,
By forming the partition plate as a separate body from the lid, partition plates having different partition division modes (for example, a partition plate divided into 4 to 12
It can be replaced with a divided partition plate), and regions having different modes can be easily analyzed. By using this characteristic local decomposition treatment jig, it is possible to easily achieve depth direction impurity analysis for each of a plurality of local regions of a sample wafer, which has been difficult to analyze in the past.

Further , according to the present invention, the partition plate is pressed against the surface of the sample wafer to be processed by the lid body screwed onto the wafer mounting body, and the lower end of the partition plate is in close contact with the surface of the wafer to be processed. Therefore, it is possible to prevent the chemical solution for etching decomposition from leaking to the outside and to prevent the chemical solution for etching decomposition on the divided surfaces to be mixed. Since the partition plate performs depth direction impurity analysis for each of a plurality of local regions of the sample wafer, the partition plate divides the surface to be processed of the sample wafer placed on the wafer holder into a plurality of regions. Is desirable.

Further, the partition plate is formed in a thin plate shape having a thickness of 3 mm or less, or the partition plate portion contacting the surface to be processed of the sample wafer is formed in an edge shape having a thickness of 3 mm or less. desirable. Thus, the partition plate is a thin plate having a thickness of 3 mm or less, or at least the partition plate portion abutting the surface to be processed of the sample wafer has a thickness of 3 m.
By forming the edge shape of m or less, it can be brought into close contact with the surface to be processed of the sample wafer, and the adverse effect that the chemical solution for etching decomposition leaks to the outside can be prevented. In particular, when the partition plate is pressed against the surface to be processed of the wafer by the lid, the lower end portion of the partition plate is deformed so that the partition plate comes into closer contact with the surface to be processed of the wafer. It is possible to completely prevent the chemical liquid from leaking.

Further, the angle of the edge of the portion of the partition plate that comes into contact with the outer peripheral portion of the surface to be processed of the sample wafer is 30 to 6 degrees.
It is preferably formed at 0 degrees. This is for facilitating the deformation of the contact portion. More preferably, the angle of the edge of the portion of the partition plate that comes into contact with the outer peripheral portion of the processed surface of the sample wafer is formed to be approximately 45 degrees.

Further, the partition plate is formed concentrically with respect to the surface to be processed of the sample wafer, and the surface to be processed of the sample wafer mounted on the wafer mounting body is provided in the outer peripheral region, the intermediate region and the central region. It is desirable to be configured to be divided into three areas. Further, the partition plate is formed concentrically with respect to the surface of the sample wafer to be processed, and the partition plate is formed in a radial direction.
Formed linearly with an interval of 4 degrees, and the surface to be processed of the sample wafer placed on the wafer holder is further divided into four areas in each of the outer peripheral area, the intermediate area and the central area, and divided into 12 areas. It is desirable to be configured in.

As described above, in the embodiment in which the divided area is divided into the three areas of the central circular area, the intermediate annular area and the outer annular area, the impurity profile in the depth direction of each of these areas can be easily obtained. As a whole, the impurity distribution in the vicinity of the wafer surface can be grasped two-dimensionally or three-dimensionally. As a result, for example, it is possible to quantitatively compare the contamination states of the outer peripheral area of the wafer, which is generally said to be most easily contaminated, and the central area, which is relatively less contaminated. Then, from this analysis result, it is possible to accurately grasp the external contamination state in each step such as the heat treatment step, and it is possible to reflect the examination result in the subsequent wafer processing and take appropriate countermeasures. . In addition, each of the above three sections is further divided into four 12
By using this for the local decomposition treatment jig for the partitioned area, it becomes possible to grasp the complete state of local impurity distribution in each portion over almost the entire area of the wafer. Further, according to the present invention, the above-mentioned local decomposition treatment jig is used to partition into a plurality of areas, wet etching decomposition of an equal depth is performed in each of the partitioned areas, and the decomposition solution is collected. A sample using a local decomposition treatment jig characterized by obtaining the three-dimensional impurity distribution of the wafer by repeating the above decomposition and collection a predetermined number of times in each partitioned area and performing impurity analysis in each decomposition solution. A method for analyzing impurities in a wafer is provided. According to this method, the three-dimensional impurity distribution of the sample wafer can be easily obtained.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a view showing a local decomposition treatment jig in which a surface to be treated of a sample wafer is divided into three,
FIG. 2A is a plan view, FIG. 2B is a sectional view taken along line AA shown in FIG. 2A, and FIG. 2 is a view showing a local decomposition treatment jig in which a surface to be treated of a sample wafer is divided into 12 parts. (A) is the top view, (b) is a BB sectional view of (a). In addition, when it is the same or equivalent member as the conventional disassembly processing tool, the same code | symbol is attached | subjected in FIG.

As shown in FIGS. 1 and 2, the local decomposition processing tool 1 according to the present invention has a wafer mounting body 11 having a circular wafer mounting surface, and is mounted on the wafer mounting body 11. It is composed of a chemical liquid holding member 13 for holding the chemical liquid for etching and decomposition applied on the sample wafer 12, and a partition plate 2 arranged in the through opening 13a of the chemical liquid holding member 13. The chemical liquid holding member 13 is made of a cylindrical tube as in the conventional case, and the partition plate 2 is housed in the through opening 13 a of the chemical liquid holding member 13. The partition plate 2 has a surface to be processed of the sample wafer 12 mounted on the wafer mounting body 11 in a plurality of regions, specifically, three regions in the embodiment of FIG. In the embodiment shown, it is divided into 12 areas. Further, as the chemical liquid holding means in the embodiment shown in FIGS. 1 and 2, the wafer mount 11, the chemical liquid holding member 13, and the partition plate 2 correspond.

In the local decomposition treatment jig of the form shown in FIG. 1, the partition plate 2 is a cross-shaped partition plate support formed so as to contact the side wall of the through opening 13a of the chemical solution holding member 13. It comprises a body 2d and ring-shaped partition plates 2a, 2b, 2c provided on the lower surface of the partition plate support 2a. When the partition plate 2 is mounted, the ring-shaped partition plates 2a, 2b, 2c are The lower end is in contact with the surface to be processed of the sample wafer 12 and the wafer to be processed is divided into three annular areas, that is, an outer peripheral area 3a, an intermediate area 3b and a central area 3c.

In the local decomposition treatment jig of another embodiment shown in FIG. 2, the partition plate 2 is in contact with the side wall of the through opening 13a of the chemical liquid holding member 13 as in the case of FIG. Cross-shaped partition plate support 2d
And ring-shaped partition plates 2a, 2b, 2c provided on the lower surface of the partition plate support 2a. Further, in the local disassembly processing jig of this embodiment, four linear partition plates 2e extending in the radial direction from the center are further formed below the cross-shaped partition plate support 2d. . The partition plate 2e is formed with an interval of 90 degrees, and its lower end is in contact with the surface to be processed of the sample wafer 12. With such a local decomposition treatment jig, the three annular regions of the outer peripheral region, the intermediate region, and the central region of the surface to be processed of the sample wafer are further divided into four regions, and the regions 31a to 3 are divided into 12 regions.
4a, 31b to 34b, 31c to 34c.

Therefore, in the local decomposition treatment jig of the present invention, the decomposition etching process for each section of the sample wafer can be performed, whereby the depth direction profile of the local impurity concentration in each region in the surface of the sample wafer is obtained. Can be asked.

The partition plate 2 of the present invention may be shaped appropriately according to the local position of the wafer for which analysis and measurement are desired, and the partitioning mode is not limited to the partitioning described above. It ’s not one, it ’s divided into two,
It may be set to any desired divisional division such as three divisions.
Further, the partition plate 2 may be a separate body from the chemical liquid holding member 13, but by being integrally formed, the chemical liquid holding member 13 is mounted on the sample wafer 12 and at the same time, the sample wafer 12 to be processed is processed. The surface can be divided into a plurality of sections, and the partition plate 2 can be mounted more easily than when the partition plate 2 is a separate body.

The plate thickness of the partition plate in contact with the wafer processing surface is not particularly limited, but it is preferable that the effective etching processing surface is as wide as possible, and it is preferable that it is as thin as possible. Usually, the thickness is set to about 1 to 15 mm. In particular, it is desirable that the partition plate is formed in a thin plate shape having a thickness of 3 mm or less, or at least a portion in contact with the surface to be processed of the sample wafer has an edge shape of 3 mm or less. Since the lower end of the partition plate and the surface to be processed of the wafer are in close contact with each other, it is possible to prevent the chemical solution for etching and decomposition of the divided surface to be processed from being mixed. In particular, when a load is applied to the upper surface of the partition plate to bring the partition plate into pressure contact with the surface to be processed of the sample wafer, the lower end of the partition plate comes into closer contact with the wafer processing surface, so It is possible to further prevent the chemical solution for etching decomposition from being mixed.

Including the partition plate 2, the constituent materials of the lid 13 of the jig, the wafer holder 11 and the like according to the present invention are the same as those of the conventional jig, such as polytetrafluoroethylene resin (PTF).
It is preferably formed from E).

Next, a second embodiment according to the present invention will be described with reference to FIGS. FIG. 3 is an exploded side view of the local decomposition processing tool according to this embodiment, and FIG. 4 is a bottom view of the chemical liquid holding means. In the figure, reference numeral 4 is a wafer mounting body having a wafer mounting surface 4a for mounting the sample wafer 12 on the upper surface thereof, and the screw portion 4 on the outer peripheral side surface thereof.
b is formed. Reference numeral 5 is a partition plate that holds the chemical solution for etching and decomposition applied on the sample wafer. The partition plate 5 has leg portions 5a, partition portions 5b that partition the outer peripheral portion of the sample wafer 12, and the sample wafer 12 And a partition portion 5c for dividing the surface to be processed. The partition portion 5b is formed in an annular shape and partitions the outer peripheral portion of the sample wafer 12. Further, the partition portion 5c is formed in a cross shape, and divides the surface to be processed of the sample wafer 12 into four.

Further, the portions of the partition portions 5b and 5c that come into contact with the surface of the sample wafer to be processed are formed in an edge shape of 3 mm or less, and the angle θ of the edge of the portion of the partition portion 5b that comes into contact with the surface of the sample wafer to be processed is θ. ₁ is formed at 30 to 60 degrees. In addition, the angle θ ₂ of the edge of the portion of the partition 5c that comes into contact with the surface to be processed of the sample wafer is formed to be 60 degrees to 120 degrees. Particularly, it is preferable that the edge angle θ ₁ of the partition plate 5b is formed to be approximately 45 degrees, and the edge angle θ ₂ of the partition portion 5c is formed to be approximately 90 degrees. The edge angle is thus defined so that even if the partition plate 5 is distorted or the like, the lower end portion of the partition plate 5 can be easily pressed by pressing the partition plate 5 against the surface to be processed of the sample wafer. This is because it can be deformed and brought into close contact with the surface to be processed of the wafer.

Further, the portions of the partition portions 5b and 5c which come into contact with the surface to be processed of the sample wafer are located above the bottom surface of the leg portion 5a, and the difference in height between them is the height of the wafer mounting surface 4a. It is formed smaller than that. That is, when the partition plate 5 is placed on the surface to be processed of the sample wafer, the legs 5a are formed at a height that does not contact the intermediate step 4c of the wafer holder 4. Reference numeral 6 is a lid 6 for pressing the partition plate 5 against the surface of the sample wafer 12 to be processed, and a screw portion 6a that is screwed with the screw portion 4b is formed on the inner side surface thereof. An opening 6b is formed on the upper surface of the lid body 6 so that the chemical solution for etching and decomposition can be injected into the wafer processing surface divided by the partition plate 5. The upper side wall 6c forming the opening 6b is formed at substantially the same position as or inside the side wall 5d that divides the outer peripheral portion of the wafer in the partition plate 5.

As described above, since the upper surface side wall 6c forming the opening 6b is formed at substantially the same position as or inside the side wall 5d partitioning the outer peripheral portion of the wafer in the partition plate 5, the screw portion 6a of the lid 6 is formed. The screw part 4b of the wafer holder 4
The upper surface 6d of the lid 6 is screwed with the partition plate 5
The entire upper surface 5d can be pressed. The partition plate is pressed against the surface to be processed of the sample wafer by this pressing force. As a result, since the lower end portion of the partition plate 5 comes into close contact with the surface to be processed of the wafer, the chemical solution for etching and decomposition is prevented from leaking to the outside, and the chemical solution for etching and decomposition on the divided surfaces to be processed is mixed. Can be prevented. In particular, since the lower end of the partition 5b for partitioning the outer peripheral portion of the sample wafer 12 is in close contact with the surface to be processed of the wafer, it is possible to prevent the chemical solution for etching decomposition from leaking to the outside.

In the above embodiment, the chemical solution holding means corresponds to the wafer mount 4, the partition plate 5, and the lid 6. Further, in the above-described embodiment, the partition portion is described as being divided into four, but as in the first embodiment, the partition surface is formed concentrically with respect to the surface to be processed of the sample wafer. The surface to be processed of the sample wafer mounted on the mounting body may be divided into three regions of an outer peripheral region, an intermediate region and a central region, and the partitioning part is provided with respect to the surface to be processed of the sample wafer. The sample wafer is formed concentrically and linearly at intervals of 90 degrees in the radial direction, and the surface to be processed of the sample wafer mounted on the wafer mounting body is divided into three regions: an outer peripheral region, an intermediate region, and a central region. 4 more each
It may be divided into 12 divisions. Further, the partition plate 5
By preparing partition plates 5 having the same outer dimensions as those of the different division styles and exchanging with such a chemical solution holding member 5,
The division style can be changed easily and in a short time. Further, in the above-mentioned embodiment, the edge of the lower end of the partition plate 5 is described. However, depending on the material of the partition plate 5 and the like, the partition parts 5b and 5c are thin plates with a thickness of 3 mm or less. However, it is not necessary to form the lower end portion into an edge shape.

In order to analyze and measure the impurity distribution in the local depth direction of a wafer made of, for example, Si or SiO ₂ using the local decomposition treatment jig shown in the second embodiment of the present invention,
First, the sample wafer 12 to be processed is mounted on the wafer mounting surface 4a above the wafer mounting body 4, and then the partition plate 5 is mounted thereon. After that, the lid 6 is covered from above the partition 5 so that the partition 5 is housed inside the lid 6, and the screw 6a of the lid 6 and the screw 4b of the wafer mounting body 4 are screwed together. As a result, the upper surface 6d of the lid 6 presses the entire upper surface 5d of the partition plate 5. At this time, the pressing force also acts on the leg portion 5a of the partition plate 5, but since a gap is formed between the bottom surface of the leg portion 5a and the intermediate step portion 4c of the wafer mounting body 4, the leg portion 5a is formed. The repulsive force from does not occur. As a result, the pressing force of the lid body 6 acts on the partition parts 5b and 5c, and the partition parts 5b and 5c are pressed against and contacted with the surface of the sample wafer to be processed.

In this state, a wafer etching decomposed solution is injected and loaded into each of the divided wafer-processed surfaces. As the etching decomposition liquid, the wafer is Si to S
In the case of iO _2, a chemical solution such as HF / HNO ₃ mixed acid is usually used.

Corresponding to one etching depth of the sequential etching decomposition treatment, the etching chemical solution for each section is recovered after a predetermined time has elapsed. Normally, a Si wafer is HF (38
%): HNO ₃ (68%) = 1:40 to 1: 100 when treated with a mixed acid, etching decomposition proceeds to a depth of about 1.0 μm in about 5 minutes. Repeat this operation,
A stepwise etching solution sample in the depth direction is sampled for each partitioned area, and a sample solution for analysis and measurement is prepared by a predetermined process. Cr, Fe, Cu dissolved in each analysis sample,
The trace impurity concentration of Ni or the like is quantitatively analyzed using, for example, a heating vaporization / ICP-MS (ETV / ICP-MS) measuring device. The detection sensitivity in the case where the wafer is sequentially etched and decomposed using the local decomposition treatment jig of the present invention and the concentration of trace impurities such as Cr, Fe, Cu, and Ni is quantitatively analyzed using the ETV / ICP-MS device, 0.0 for Cr and Fe
1 ng / g (3 × 10 ¹² atoms / cm ³ ), Ni and Cu
Reaches 0.005 ng / g (1 × 10 ¹² atoms / cm ³ ).

[0032]

(Example 1) A Si wafer having a diameter of 5 inches was set on the local decomposition treatment jig (divided into 3 sections) according to the present invention shown in FIG. 3, and HF (38%): HNO ₃ (68) %)
= 1: 40 mixed acid etching decomposition chemical solution was injected into the wafer outer peripheral section area 5 ml, the intermediate section area 5 ml, and the central section area 5 ml, respectively, and after 5 minutes from the injection, etching decomposition of each section The chemical solution was collected in a Teflon container and used as a sample for analysis. By repeating this operation, a sample for stepwise analysis in the depth direction for each partitioned area was obtained. After each of these analysis samples was made into a measurement sample solution by a predetermined pretreatment, the concentration of Fe, which is an impurity metal, was measured by an ETV / ICP-MS analysis device, and the wafer was measured in the outer peripheral region, intermediate region, and central region. The Fe concentration distribution in the depth direction was obtained for each section of the region. The results are summarized as a bar chart and shown in FIG.

The verification of the etching thickness for each successive etching step of each partitioned region is carried out by using a part (1
00 to 200 μm), the amount of dissolved Si is quantified by the absorbance measurement using the molybdenum blue method using the aforesaid sample solution, and the surface roughness is calculated by the method of converting from the quantitative value of the dissolved Si. It was confirmed by using a method of directly measuring with a meter.

(Comparative Example 1) Next, using the conventional local decomposition treatment jig shown in FIG. 7, the entire surface of the wafer to be processed is set as one region, and the amount of the chemical solution for etching decomposition to be injected into each of the above regions. Except for the total injection amount (15 ml), the same process as in Example 1 was performed to obtain the Fe concentration distribution in the depth direction as an average value over the entire wafer. The results are shown in FIG. 6 as a bar chart.

From the results of FIGS. 5 and 6, the distribution of trace metal impurities in the wafer in the depth direction greatly differs depending on the local area of the wafer surface, and the actual contamination state of the wafer can be accurately determined only by the distribution profile as the average value of the entire wafer surface. It was admitted that it was impossible to grasp. Also, in the conventional local decomposition treatment jig shown in FIG. 7, a small amount of leakage of the etching decomposition chemical liquid was observed. On the other hand, in the local decomposition treatment jig according to the present invention, no leakage of the chemical solution for etching decomposition was observed.

[0036]

The present invention improves a conventional disassembly processing jig for etching the entire surface of a silicon wafer, and divides the etched surface of the wafer into a plurality of regions by the partition plate of the present invention, for example, the outer peripheral region and the intermediate region. , The central area is divided into 3 areas or 12 areas, so that the in-plane local impurity distribution of the wafer peripheral area, the intermediate area, the central area, etc., which cannot be obtained easily, can be easily obtained. It was possible for the first time to accurately understand the actual state of external contamination in each processing step, including the wafer heat treatment step, through a time-sensitive process analysis. Further, according to the present invention, the partition plate is pressed against the surface to be processed of the sample wafer, and the lower end portion thereof is in close contact, so that the chemical solution for etching decomposition is prevented from leaking to the outside.
It is possible to prevent the chemical solution for etching and decomposition of the divided surface to be processed from being mixed. Further, the surface of the wafer was divided into a plurality of parts by using a local decomposition treatment jig, wet etching decomposition of the same depth was performed in each divided region, and the decomposition liquid was collected and further divided into the above. The sample wafer impurity analysis method according to the present invention is characterized in that the above-mentioned decomposition / collection is repeated a predetermined number of times in each region and impurity analysis is performed in each decomposition solution to obtain a three-dimensional impurity distribution of the wafer. Thus, the three-dimensional impurity distribution of the sample wafer can be easily obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a local decomposition treatment jig according to the present invention, in which (a) is a plan view thereof,
(B) is an AA sectional view shown in (a).

2A and 2B are views showing a modified example of the first embodiment of the local decomposition processing jig according to the present invention, in which FIG. 2A is a plan view thereof, and FIG. 2B is shown in FIG. It is the BB sectional view.

FIG. 3 is an exploded side view showing a second embodiment of the local disassembly processing jig according to the present invention.

FIG. 4 is a bottom view of the drug solution holding means shown in FIG.

FIG. 5 is a diagram showing the Fe concentration distribution in the depth direction for each of the outer peripheral region, the intermediate region, and the central region of the wafer in Example 1.

FIG. 6 is a diagram showing an Fe concentration distribution in the depth direction as an average value over the entire surface of a wafer in Comparative Example 1.

FIG. 7 is a diagram showing an example of a conventional disassembly treatment jig,
(A) is the top view and (b) is the sectional view.

[Explanation of symbols]

1 Local decomposition processing tool 2 partition boards 2a to 2c Ring-shaped partition plate 2d partition plate support 2e Linear partition plate 3a-3c division division (3 divisions) 31a-34c division division (3 divisions) 4 Wafer mount 4a screw part 5 partition boards 5a legs 5b partition 5c partition 6 lid 6a screw part 10 Disassembly tool 11 Wafer mount 12 Sample wafer 13 Chemical liquid holding member 13a through opening

Continuation of the front page (56) Reference JP-A-63-195540 (JP, A) JP-A-61-221649 (JP, A) JP-A-8-5526 (JP, A) JP-A-8-152387 (JP , A) Actual Development Sho 62-126749 (JP, U) Actual Development Sho 61-206845 (JP, U) Takenaka, Tomita, Kubota, Tsuchiya, Matsunaga, Chemical Analysis, Japan, February 5, 1994, Volume 43. No. 2, p. 173-176 (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 1/00-1/44 G01N 31/00 H01L 21/66 JISST file (JOIS)

Claims (5)

(57) [Claims] 1. A sample wafer is subjected to etching decomposition treatment,
In a local decomposition processing jig used for impurity analysis of the wafer, a wafer mounting body having a wafer mounting surface on which a sample wafer is mounted, and a sample wafer mounted on the wafer mounting body are provided. And a chemical solution holding means for holding a chemical solution for etching decomposition to be added, wherein the chemical solution holding means is at least a partition plate for holding the chemical solution for etching decomposition to be added on the sample wafer on the surface to be processed of the sample wafer, A lid body that presses the partition plate against the surface to be processed of the sample wafer, and the partition plate is provided for the sample wafer mounted on the wafer mounting body.
It is a partition plate that divides the surface to be processed into multiple areas.
Formed into a thin plate of 3 mm or less, or a sample wafer
The partition plate portion that comes into contact with the surface to be processed of
The lid is formed to have an edge shape of 3 mm or less, and an opening for injecting a chemical solution for etching and decomposing on the sample wafer is formed in the lid and formed so as to be screwed with the outer peripheral side surface of the wafer mounting body. The partition plate is configured to be pressed against the surface to be processed of the sample wafer by screwing the lid body onto the wafer mounting body. 2. The local according to claim 1 , wherein an angle of an edge of a portion of the partition plate which is in contact with the outer peripheral portion of the processed surface of the sample wafer is formed to be 30 degrees to 60 degrees. Disassembly jig. 3. The partition plate is formed concentrically with respect to the surface to be processed of the sample wafer, and the surface to be processed of the sample wafer placed on the wafer mounting body is in the outer peripheral region, the intermediate region and the central region. The local decomposition treatment jig according to claim 1 , wherein the local decomposition treatment jig is configured to be divided into three areas. 4. The partition plate is formed concentrically with respect to the surface to be processed of the sample wafer, and is 90 mm in the radial direction.
Formed linearly with an interval of 4 degrees, and the surface to be processed of the sample wafer placed on the wafer holder is further divided into four areas in each of the outer peripheral area, the intermediate area and the central area, and divided into 12 areas. The local decomposition treatment jig according to claim 1 , wherein 5. The local decomposition treatment jig according to any one of claims 1 to 4 is used to partition into a plurality of areas, and wet etching decomposition of equal depth is performed in each partitioned area, The three-dimensional impurity distribution of the wafer is obtained by collecting the decomposition solution, repeating the decomposition and collection a predetermined number of times in each of the partitioned areas, and performing impurity analysis in each decomposition solution. Method for impurity analysis of sample wafer using local decomposition treatment jig.